Evaluation of opioid peptide gene expression by solution hybridization RNase protection.

The solution hybridization RNase protection assay may be considered a suitable method for both qualitative and quantitative analysis of mRNAs. In the present study we described an application of solution hybridization RNase protection assay to the quantitative analysis of prodynorphin mRNA, which encodes for the synthesis of prodynorphin, a common precursor for a number of opioid peptides. In the myocardial cell, stimulation of the K opioid is involved in the modulation of cytosolic calcium and pH homeostasis. In the present study, we found that prodynorphin mRNA, which encodes for the synthesis of a common precursor of opioid peptides interacting with K sites, is synthesized both in atrial and in ventricular tissue of the rat heart. In adult cultured rat ventricular cardiomyocytes, the level of prodynorphin mRNA did not differ from that detected in the original ventricular tissue. This finding indicates that the myocardial cell is an important source for prodynorphin gene expression and has the potential for an intrinsic synthesis of dynorphin-related peptides.